(a) Field of the Invention
The present invention relates to a variable valve lift apparatus with a low lift mode, a high lift mode, and a CDA mode.
(b) Description of the Related Art
A typical combustion chamber of an automotive engine is provided with an intake valve, for supplying an air/fuel mixture, and an exhaust valve, for expelling burned gas. The intake and exhaust valves are opened and closed by a valve lift apparatus connected to a crankshaft.
A conventional valve lift apparatus has a fixed valve lift amount due to a fixed cam shape. Therefore, it is impossible to adjust the amount of gas that is introduced or exhausted. However, valve timing and amount of lift should ideally be optimized for different driving speeds.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.